Historically, the pneumatic tire has been fabricated as a laminate structure of generally toroidal shape having beads, a tread, belt reinforcement, and a carcass. The tire is made of rubber, fabric, and steel. The manufacturing technologies employed for the most part involved assembling the many tire components from flat strips or sheets of material. Each component is placed on a building drum and cut to length such that the ends of the component meet or overlap creating a splice.
In the first stage of assembly the prior art carcass will normally include one or more plies, and a pair of sidewalls, a pair of apexes, an innerliner (for a tubeless tire), a pair of chafers and perhaps a pair of gum shoulder strips. Annular bead cores can be added during this first stage of tire building and the plies can be turned around the bead cores to form the ply turnups. Additional components may be used or even replace some of those mentioned above.
This intermediate article of manufacture would be cylindrically formed at this point in the first stage of assembly. The cylindrical carcass is then expanded into a toroidal shape after completion of the first stage of tire building. Reinforcing belts and the tread are added to this intermediate article during a second stage of tire manufacture, which can occur using the same building drum or work station.
This form of manufacturing a tire from flat components that are then formed toroidally limits the ability of the tire to be produced in a most uniform fashion. As a result, an improved method and apparatus has been proposed, the method involving building a tire sequentially on a core or toroidal body. The core or toroidal body rotates about its axis as tire components are applied layer by layer to the outer core surface. When the tire build procedure is completed on the core, the green tire will have a shape and dimension only slightly smaller than the finished tire. The aforementioned variances resulting from conventional drum expansion are thus eliminated. Building a tire on a core to a final tire shape, dimension, and uniformity therefore allows for improved quality control of the finished product.
Once component by component tire build is accomplished on the core, the green tire must be subjected to heat during a curing cycle. The tire and core may be as a unit subjected to heat within a curing cycle whereby the green tire is cured. It is important to maintain structural integrity of the annular tire building surface throughout the tire curing cycle and readily facilitate a subsequent separation of the core from the cured tire.